This invention relates to an energy storage and power system, and in particular an energy storage and power system that is of a hybrid design which combines existing, market proven components in a unique design which provides for the high efficiency capture, conversion, storage and production of energy.
This invention includes a gravitational component to maximize the conversion, transfer and storage of energy, streamline the design and increase overall system efficiency. The system is scalable in size and capacity.
This invention has many applications and there are many architectures upon which the same basic purpose, function and operation can be achieved by altering the general system described herein.
Therefore, it is understood that this patent application shall include all deviations of this design and reference same herein, and that the illustrative design described herein is just one possible design, function, use and operation of the fundamental invention.
The purpose of this invention is to provide a highly efficient compartmentalized and expandable energy storage system, used for, in some embodiments, storage and distribution of energy.
This embodiment of the invention is an electric, hydraulic and gravitational hybrid energy storage system that may be used in an electric utility grid application to store electrical generation overcapacity. The stored energy may be provided to the electrical utility grid when there is increased demand.
Further, this invention may be considered a load leveling system for the utility grid. Leveling the electrical load is a needed function of the utility grid, from a seasonal, weekly, daily, hourly and even a fractional hourly perspective. Wildly fluctuating electrical loads are destructive to the utility grid, and load leveling decreases the stress applied to the grid and makes the production of energy more cost effective, reliable and efficient.
There are many energy storage systems in place which serve as load leveling devices such as batteries, flywheels, gravitational, chemical and pneumatic systems. These systems are all being used to store energy and to balance the electrical grid. All of these systems have their own strengths, weaknesses and efficiencies.
Compressed air energy storage (CAES), gravitational pumped hydro, flywheel and different battery chemistry storage systems are all in operation, with compressed air and pumped hydro being the least expensive in terms of long term costs and yet the most inflexible in terms of location/use, and the flywheel and battery systems which have much higher costs but are most flexible in terms of location/use.
Battery storage is an obvious choice for utility industry, as both the A/C energy that the utility operators produce and the batteries which store energy are both electrical in nature requiring only the conversion of the current (A/C to D/C or D/C to A/C) to be effective. Battery only based energy storage systems rely solely on the batteries to provide all of the energy when the demand is placed upon them. The high current draws experienced in battery only based energy storage systems may be detrimental to the life span of the batteries and associated electronics.
Batteries, regardless of chemistry, either have high power density or high energy density, but not both. When designing a battery storage system, the specific uses and needs of the application will dictate power dense or energy dense chemistries. Further, the battery is the only device in a battery based storage system which may accept and discharge energy. This is not economically viable because charging and discharging batteries at high rates are detrimental to the batteries chemistry and shorten the batteries service life, which increases long term operation and maintenance costs.
In order to reduce these costs and optimize the batteries life span, discharge rates should be low and even. This is not possible in a battery only storage technology as large current draws are a matter of function. Deep and repeated charge/discharge rates kill batteries. A battery management system must monitor all the batteries voltages and temperatures which is expensive and complicated. There is research and development to improve battery chemistries, but a near term solution has not been found as of this writing.
What is needed is an alternative to centralized battery energy storage facilities as they exist today, one that provides the energy density needed to operate a system that may provide meaningful grid balanced and high current output over a period of time with less destructive high charge/discharge rates.
Another example of an energy storage system that needs improvement is gravitational pumped hydro. Pumped hydro has the largest share of the installed energy storage capacity market due to its simplicity and its power density. However, there are many problem associated with pumped hydro, including geographical placement, environmental and facility installation cost, environmental impacts on existing ecosystems and the amount of time between conception and operation can and has taken decades.
The placement of a pumped hydro facility requires a substantial elevation difference in close proximity to both the upper and lower water reservoirs which is not always near electrical transmission or distribution infrastructure. The absence of these facilities requires expensive transmission lines to be installed to operate with the pumped hydro facility.
Also, the required economic capital is immense and includes a lengthy site selection process, environmental impact studies which can cost millions, construction costs which may total hundreds of millions of dollars and then there are the long term operational and maintenance costs.
The advantages of using gravitational pumped hydro energy storage are low specific energy costs, long lifetime, low maintenance, reasonable energy density and good reliability. The disadvantages of using pumped hydro energy storage are significant geographical placement hurdles as there must be a significant difference in elevation between the two bodies of water, high up front capital and environmental study costs, a decade or more of planning and construction, and finding geographical locations which are near electrical transmission and distribution facilities.
What is needed is an alternative to the centralized pumped hydro energy storage facilities as they exist today, one that may provide the power density needed to provide meaningful grid balanced and high current output over a period of time with less costs and fewer installation site restrictions, and yet use the same efficient gravitational functionality provided by pumped hydro systems.
Another example of an energy storage system that needs improvement is Compressed Air Energy Storage, or CAES. CAES is similar to pumped hydro in that the site itself is large and the site selection process is both lengthy and restrictive. Underground caverns that are large enough and strong enough for meaningful energy storage are not easily found. There are only so many abandoned salt mines or natural caverns. Lengthy and expensive environmental impact studies are also required of a CAES facility. Also, geographically satisfactory locations for CAES systems are rarely near electrical transmission or distribution infrastructure, which requires expensive transmission lines to be installed to operate the CAES facility.
Further, a CAES system requires a fueled power plant that utilizes the compressed air to make the cost of producing energy less expensive. And while the compressed air may improve the efficiency of the fueled power plant, CAES does not provide a standalone and emission free energy storage system. What is needed is an alternative to centralized and site restrictive CAES facilities as they exist today and yet use the efficient functionality of gas compression and expansion similar to a CAES system.
The advantages of using compressed air energy storage (CAES) are low specific energy costs, long lifetime, low maintenance, reasonable energy density and good reliability. The disadvantages of using compressed air energy storage (CAES) are significant geographical and subterranean placement hurdles, high up front capital costs and finding geographical locations which are near electrical transmission and distribution facilities. Further, current compressed air energy storage (CAES) technologies use the compressed air to assist a fueled power plant, which produces undesirable environmentally damaging emissions.
Examples of energy storage systems are found in U.S. Pat. No. 7,281,371 B1 to Heidenreich, U.S. Pat. No. 7,963,110 B2 and US20100307156A1 to Bollinger (isothermal expansion control) and others, U.S. Pat. No. 7,770,331 B2 to Halloran, all of which are incorporated fully herein by reference.
An issued U.S. patent for an energy storage and distribution device that uses principals that are similar to the present invention by combining the attributes of pumped hydro (PH) and compressed air energy storage (CAES), but does not use batteries or a gravitationally aided drive system, was issued on Oct. 16, 2007 and is titled “Compressed Air Pumped Hydro Energy Storage and Distribution System” (U.S. Pat. No. 7,281,371 B1) to Heidenreich, incorporated fully herein by reference. Heidenreich teaches the art of using water and air with elevation and pressure differential to store energy.
In the preferred Heidenreich embodiment, during times of excess capacity in the electrical grid, electricity is used to move water from an area of greater elevation, such as an atmospherically exposed reservoir, to an area of lower elevation, such as a sealed subterranean enclosure which has an area of enough volume to receive the reservoirs volume of water and yet still allow an area of volume to provide a space where the compression of a volume of air may occur. Said subterranean enclosure may also be abandoned mine shafts, salt mines, or other subterranean areas which may be suitable for effective operation of the Heidenreich patent.
In Heidenreich, the movement of water is accomplished with the use of a fluid pump/motor and an electrical motor/generator. During energy storage, the electric motor/generator operates as an electric motor which operates a fluid pump/motor as a pump and moves a volume of water from the atmospherically exposed reservoir through an inter-connecting tube to the sealed subterranean enclosure. This causes the pressure of the volume of air in the sealed enclosure to rise, storing potential energy.
In “power generating application”, the compressed air forces the water in the sealed subterranean enclosure to move through the inter-connecting tube and to the atmospherically exposed reservoir. This movement causes the fluid pump/motor to operate as a motor which operates the electric motor/generator as a generator, thereby generating electrical energy which may be exported to an electric grid.
Heidenreich also teaches that an air compressor may be provided which may be powered electrically from excess electrical energy capacity in the grid, and is pneumatically connected to the sealed subterranean enclosure to provide both initial pressurization of the sealed subterranean enclosure and replace decreasing air and pressure in the sealed subterranean enclosure due to system operation and/or leaks.
Additionally, Heidenreich also teaches several configurations and embodiments, such as using a second subterranean enclosure which is atmospherically vented instead of an atmospherically exposed reservoir and having said atmospherically vented subterranean enclosure placed at a higher subterranean elevation than the first sealed subterranean enclosure, effectively producing the same result when the Heidenreich invention operates.
Further, Heidenreich teaches that the compressed air in the sealed subterranean enclosure(s) may also provide the compressed air needed during the combustion process in a natural gas powered electrical energy generation facility, rather than having the natural gas powered electric generator consume real time energy to compress the air required for combustion.
However, while Heidenreich similarly combines many aspects of pumped hydro and CAES, Heidenreich does provide a means to reduce the size of the combined energy storage system in such a way as to allow compartmentalization on a scale which may allow an attribute combining energy storage system to be placed in virtually any environment, altitude or location and provide energy storage, production and distribution, as provided by the present invention.
Also, Heidenreich does not teach using gas charged hydraulic accumulators to combine the area for a volume of fluid and a volume of compressible gas, such as provided by the present invention. Using a gas charged hydraulic accumulator provides the ability to use nitrogen as the compressible gas, which has higher expansive properties when compared to ordinary air, thereby increasing the efficiency of the system overall. Further, the nitrogen gas in the gas charged hydraulic accumulator is sealed, allowing the system to operate without the use of any air contaminate filtration device or gaseous filtration system, which would be required with the Heidenreich patent. If any explosive gases were to enter the Heidenreich system and become compressed, and an ignition source such as an electrical failure or lightning ignited the mixture, the results could be catastrophic. This potentially fatal aspect of the Heidenreich patent is eliminated with the present invention.
Additionally, Heidenreich does not mention, beyond the scope of the stated functionality of Heidenreich, the use of belts, cables or any other mechanical device to operate a hydraulic pump to move a volume of fluid from an atmospherically vented reservoir to a sealed enclosure such as the gas charged hydraulic accumulator as provided in the present invention. Nor does Heidenreich disclose the combining or grouping of smaller attribute combining energy storage devices to provide any given or required energy storage or production capacity as provided by the present invention.
Further, Heidenreich does not disclose or teach using the components of the combined attribute energy storage system as the weighted component of a gravitationally aided energy storage device which converts, stores and produces energy. The present invention allows gravity to operate mechanical devices which may help move a volume of fluid in order to compress a gas and store potential energy.
Further still, Heidenreich does not teach a method of combining the output of individual combined attribute energy storage systems to provide user definable and demand regulated electrical energy production as the present invention discloses.
Even further, Heidenreich does not teach an operational attribute that separates and makes independent the capture and storage of energy being placed into the energy storage system and the hydro-pneumatic production of energy as taught in the present invention.
An issued U.S. patent for an energy storage and distribution device that uses principals that are similar to the present invention by combining the attributes of pumped hydro (PH) and compressed air energy storage (CAES), was issued on Jun. 21, 2011 and is titled “System and method for improving drivetrain efficiency for compressed gas energy storage” (U.S. Pat. No. 7,963,110 B2) to Bollinger and others, incorporated fully herein by reference. Bollinger teaches the art of providing a constant output from a decaying or fluctuating input pressure using staged accumulators. Bollinger does not teach using any of the components of the Bollinger patent as a part of the weighted component in a gravity-aided energy storage system as described by the present invention.
Another issued U.S. patent for an energy storage and distribution device that uses principals that are similar to the present invention by combining the attributes of pumped hydro (PH) and compressed air energy storage (CAES), was issued on Aug. 10, 2011 and is titled “Potential energy storage system” (U.S. Pat. No. 7,770,331B2) to Halloran, incorporated fully herein by reference. Halloran teaches the art of providing an energy storage system using a weighted structure, such as a buildings support beams, that is hydraulically lifted and then lowered to provide energy for hydraulically generated electricity. Halloran does not teach using any of the components of the Halloran patent as a part of the weighted component in a gravity-aided energy storage system as described by the present invention. Further, Halloran does not disclose the ability to add capacity at any time, nor does Halloran teach using the system outside of a buildings structure or at the top of a buildings structure.
While all of these existing forms of energy storage all have their own specific benefits, they also have economic, environmental and operations flaws which provides the need for improving the current state of the art in energy storage. Ideally, combining the attributes of some or all of the existing technologies into one energy storage system may provide a real and meaningful improvement to energy storage, especially if the improvement reduced or eliminated economic, environmental and operational flaws associated with the individual existing technologies.
The challenge continues to be to provide a low cost, highly efficient energy storage system that is flexible in location and use and provides a scalable and dynamic energy storage system that the utility companies may utilize for demand response, a form of spinning reserves, bridging power, dynamic response, load leveling, load shifting, load reduction and demand side management and other ancillary service while commercial end users may mitigate or eliminate peak energy costs by reducing utility provided energy and associated demand charges during peak energy times by using cost and time shifted energy in storage devices and/or systems.
Combining the different systems into one hybrid design allows the best attributes of each individual technology to be maximized at their highest efficiencies and provides a better overall solution. Adding a gravitational component aids in the transfer of energy at a high rate of efficiency.
Using a combination of existing electrical and hydraulic components, a new energy storage system is invented with a unique gravitational energy conversion and transfer system which provides high storage efficiency, reduces the strain on the batteries by eliminating the high current draw associated with battery energy storage systems and by segmenting the batteries to power their own unit or groups of units, eliminates the geographical placement hurdles associated with pumped hydro and compressed air energy storage, reduces the electric frequency regulation system complexity of other energy storage systems and associated costs while providing significant value to the utility providers and the end users.
The present invention provides a hybrid mix of the existing technologies in a novel and unique way which allows energy to be stored in an efficient and cost effective manner. Batteries are used for the main energy storage system, but are not relied upon to provide the heavy discharge currents associated with other battery energy storage systems. Hydraulically driven electrical generators provide the frequency matched electrical energy required for any application. Simple and inexpensive components lower long term operational and maintenance costs. Where hundreds or thousands of identical units are installed, only a handful of maintenance components are needed for servicing as the units are identical, leading further still to reduced manufacturing/assembly costs.
The present invention utilizes the attributes of pumped hydro using gravity assisted fluid transfer by mechanical means. The present invention also combines pumped hydro's fluid transfer with Compressed Air Energy Storage (CAES) functionality by powering hydraulic pumps and motors to transfer fluid from one vessel to another vessel during storage and power generation modalities. This feature allows conventional and existing market proven components to make the capture, conversion, storage and production of energy more safe, effective and affordable while eliminating hazardous conditions associated with high temp chemical energy storage systems, flywheel energy storage systems high speed explosive possibilities and the placement issues associated with such large scale pumped hydro and CAES systems, while extending a battery based energy storage systems battery service life.